Simple fact—the smaller the recorder, the more piercing it is. By that logic, you want a F bass (or more accurately ‘basset’) as they are quite soft in sound projection compared to even a tenor. Yes, a bass is a bit pricey, but the highest note (which you’ll likely rarely play) is G—the second G on the alto. Basses don’t carry very much, although IF your apartment is wood construction, you may want to think hard. The places like that I’ve lived in when I was single were pretty thin walls/floors, yet I DID get away with it. Try also to practise/play when your neighbours are out if you can. If you are in a concrete constructed high-rise, you’re good to go! Nothing to worry about. I play a VERY FULL sounding Bressan alto in our place and nobody can hear it.
FYI: I’m an apartment dweller who has lived in them all for over 40 years—and still.
Mainly French & English baroque repertoire on an A403 Bressan, and an A415 DeBey. Recorder enthusiast since 1971. Early Music program at York University, French baroque instruction at Royal Conservatory in Toronto.